1. Field of the Invention
The present invention relates to the detection of fungi, particularly the detection of pathogenic fungi in building materials.
2. Description of the Related Art
The growth of fungi, such as certain types of black or gray molds in residential and commercial buildings, can produce significant health hazards to the human occupants thereof. For example, the black molds known as Stachybotrys and Memnoniella are types that are known to produce mycotoxins which are hazardous to human health upon exposure to these toxins. These mold types typically occur on repeatedly wetted materials that contain cellulose, for example, interior wall paneling, such as gypsum board, and other materials used in residential and commercial buildings including cardboard, ceiling tiles, cellulose insulation, wood, etc. See Andersson et al., 1997; Burge et al., 1999; Croft et al., 1986; Haugland et al., 1999; Leenders et al., 1999; Levetin, 1995; Sorenson et al., 1987; Stetzenbach, 1997; and Vesper et al., 2000; the entire contents and disclosures of each and all of which are incorporated herein by reference.
There are several sources of moisture which can accelerate and promote the growth of gray and black molds including the types mentioned above. Water piping extending through plumbing chases and piping extending through voids or spaces in interior walls of residential and commercial buildings can produce minute leaks sufficient to wet adjacent materials and promote the growth of mold. Leakage from the exterior of a building into various parts of the building, which goes undetected, can also wet the surfaces of various materials which would promote the growth of toxic molds. Still further, condensation, from time to time, on the surfaces of plumbing piping, air conditioning ducts, refrigerant conduits and other structures is also a source of moisture which can result in the growth of molds in unseen spaces, such as the interior wall spaces of buildings, among other locations, all of which are a source of mold contamination that humans are exposed to.
The growth of mold in interior wall spaces in residential and commercial buildings is particularly difficult to detect and difficult to eradicate by conventional methods. Since the interior wall spaces have been covered with various types of wall paneling, the growth of mold goes undetected and, when detected, is difficult to treat without major renovation of the building. Accordingly, there has been a longstanding need for the development of rapid and efficient mold detection methods and systems that will identify those areas in need of treatment to eradicate toxic mold infestations.
Methods are known for the quantitative determination of molds and fungal pathogens; however, such methods require the isolation and purification of genetic material (e.g., DNA) from the suspected fungi or the isolation of the mold and culturing thereof before analysis can take place.
U.S. Pat. No. 6,387,652 relates to the use of PCR or other molecular techniques to quantify the presence of fungi and bacteria; however, the methods disclosed require “extracting and recovering DNA” from the suspected organism.
Similarly, US application publication 20030054369 also requires the isolation and purification of the suspected DNA before quantitation thereof in the sample.
U.S. Pat. No. 5,580,971 discloses methods for the detection of particular genera or species of fungus in biological samples. The methods use a solid support-polynucleotide structure that includes a solid support having immobilized thereon a polynucleotide probe that is complementary to a sequence of ribosomal RNA (rRNA) specific to a particular species of fungus.
U.S. Pat. No. 5,707,802 discloses nucleic acid probes and primers for detecting fungi. The probes can detect rRNA, rDNA or polymerase chain reaction products from a majority of fungi in clinical, environmental or food samples. The methods disclosed all require the extraction and isolation of the nucleic acid from the suspected fungi.
U.S. Pat. No. 5,753,467 describes a method for the identification of fungi that requires first isolating DNA from the suspect material; the isolated DNA having variable sequences interspersed between highly conserved rDNA sequences. The variable sequences are amplified in such manner as to either amplify the variable sequences interspersed between highly conserved rDNA sequences or to amplify arbitrary genomic regions in conjunction with the variable sequences.
U.S. Pat. No. 5,919,617 describes methods and materials for detecting the presence of a fungus in biological samples.
US application publication 20020098487 discloses nucleic acids for detecting fungi that may be used as probes or primers for gene amplification and as primers for the detection and identification of fungi belonging to the genus Aspergillus in biological samples. Isolation of the target nucleic acid material is required.
US application publication 20030039981 provides a method and material for detecting the presence of a fungus in a biological sample. The method requires the isolation of the suspected DNA from the sample.
US application publication 20030099946 and US application publication 20030099975 relate to the use of primers in polymerase chain reaction assays for the detection of fungal pathogens Colletotrichum acutatum, Alternaria spp., and Cladosporium carpophilum. The methods require extracting and isolating DNA from an organism.
The above cited methods, however, are time consuming and expensive because they require the isolation and purification of the nucleic acids, thereby rendering them inefficient and inconvenient in situations where all that is required is a qualitative screening for the presence of the mold. The entire contents and disclosures of each and all of the above listed patents are incorporated herein by reference.
Citation of any document herein is not intended as an admission that such document is pertinent prior art, or considered material to the patentability of any claim of the present application. Any statement as to content or a date of any document is based on the information available to applicant at the time of filing and does not constitute an admission as to the correctness of such a statement.